They should have offered for acceptance the name of the alternative person before they appointed them. You would have then had to accept or not accept the alternative person. A reason for not accepting them is they are not equally qualified or experienced.
It is up to you I guess what you do about this now, but you would still be within your rights to accept or not accept even now.
It is up to you I guess what you do about this now, but you would still be within your rights to accept or not accept even now.